WhatsApp will soon be introducing free voice calls over the app for Android and iOS users, while BlackBerry and Windows Phone will be supported later.

Jan Koum, WhatsApp's co-founder and chief executive, has revealed that the company will soon be launching voice calling capabilities on all of its apps starting with Android and iOS in the second quarter. Jan has been known to support ad-free software and believes in easy communication, which was the primary reason behind the launch of WhatsApp. In an interview with The Guardian, Jan spoke about his childhood in Russia, where neighbours used to share telephone lines and the inconveniences associated with it. To make calling simpler and free, for users across borders, voice calling is Jan's next target.

Speaking about the technology behind voice calls in WhatsApp, Jan said, "We use the least amount of bandwidth out there, and have optimised the hell out of it. We’ve made sure the quality is there, though, just like the messaging functions of WhatsApp."